Automatic choke control



AUTOMATI C CHOKE G ENTROL Filed April 11, 1932 2 Sheets-$heet l April? 21, E. E. MOORE y l AUTOMATIC CHOKE CONTROL Filei April 11, 1932 2 Sheets-Sheet 2 minim i'NVEN TOR.

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IPatented Apr, 21, 193% AUTUMATHG CHKDKE @QDNTRUL lEarl E. Moore, South Bend, 11nd, assignor to The Studebaker Corporation, South Bend, End a corporation of New Jersey Application April 11, 1932, Serial No. 604,495

1 Claim.

This invention relates to an automatic control device for the choke or priming valve of the carburetor of an internal combustion engine, and has for its principal object the provision of a control device of the character indicated which, while primarily responsive to engine temperature, will also operate the carburetor choke valve to prime the engine whenever the engine is started regardless of its temperature.

It is also an object to provide an automatic control device of the character indicated which will not operate the choke valve to prime the engine when the engine is running at a normal operating temperature, regardless of the speed at which the engine is operating.

It is a still further object to provide a control device of the character indicated which is fully automatic in character and requires no manual adjustments under any operating condition of the engine.

It is also an object of the invention to provide an automatic control means of the character indicated which is simple and economical to manufacture, is rugged in construction and will not readily get out of order in use.

Other objects and advantages of the invention will appear as the description proceeds.

The drawings illustrate two acceptable mechanical embodiments of the idea of the invention. The drawings, however, are not to be taken as limiting the invention, the scope of which is to be measured solely by the scope of the subjoined claims.

In the drawings:

Figure 1 is an elevational view of a fragmentary portion of the intake and exhaust manifolds of an internal combustion engine, a carburetor attached to the intake manifold and a control device constructed according to the idea of this invention operatively connected with the choke or priming valve of the carburetor, certain portions of the control device and of the carburetor being broken away to more clearly illustrate the construction of the control device and its application to the choke valve of the carburetor.

Figure 2 is a view similar to Figure 1, showing a somewhat modified form of control device.

Referring to the drawings in detail, and particularly to that form of the invention illustrated in Figure 1, the numeral Ill indicates the exhaust manifold of an internal combustion engine held in. operative position over the exhaust ports of the engine by means of nuts H threaded upon stud bolts secured in the engine block. The numeral 12 indicates an intake manifold foran internal combustion engine also held in operative position upon the engine by means of the nuts M. The exhaust manifold I0 is provided with a heating chamber I4 through which extends a passageway, not shown, from the carburetor E5 to the intake manifold l2.

In this illustration I have shown an updraft carburetor l5 operatively connected to the lower side ofvthe heating chamber M. It is to be understood, however, that the application of the device of this invention is not limited to a carburetor of this form and could for instance, with equal facility, be applied to a carburetor of the downdraft type which would be mounted above the intake manifold l2.

The carburetor is provided with an air intake it in which is pivotally mounted a butterfly valve 2% adapted, when in the position indicated by the dotted lines, to close the air intake i8 and cut off the air supply to the carburetor, thereby enriching the fuel mixture fed to the engine. A small spring tension valve H is provided in the butterfly valve to permit a limited amount of air to flow through the air intake to the carburetor even when the choke valve 21] is in its fully closed position.

In order to provide for the fully automatic control of the choke valve 20, I have provided the following structure. Mounted upon a fixed portion of the engine by means of a suitable bracket or other anchoring means, and positioned above the manifolds ill and i2 is a cylindrical casing 23?. Mounted co-axia-lly within the upper portion of the casing 23 is a solenoid 25 provided with an axial aperture within which the armature 26 is adapted to reciprocate. One side of the solenoid is grounded at 28 and the opposite side is connected to the lead from the generator G to the battery B between the generator and the circuit breaker or relay R, whereby the solenoid will be energized whenever the generator is operating,

and only when the generator is operating.

A vent 30 is provided through the top of the cylindrical casing 23 opening into the axial aperture in the solenoid 25 above the armature 26. This vent is connected to the interior of the intake manifold 62 by means of the tube 3|, connections 32 and 33 and elbow joint 34. If so desired, the elbow joint 34 may be a T-joint, one side of which is operatively connected with a vacuum actuated windshield wiper, not shown.

A-rod 35 is slidably mounted in an axial bore 36 extending into the armature 26 for the major portion of its length, but having a closed end at the upper end of the armature. This rod 35 projects below the lower end of the armature 26 and the lower end of the rod 35 is connected by means of a rod 38, which may be a Bowden wire or other suitable connecting element, with the free end of an arm 39, the opposite end of which is rigidly connected to a projecting end of the shaft 40 upon which the butterfly valve 20 is mounted. It will be observed from this description that vertical motion of the rod 35 will be transmitted through the rod 38 and arm 39 to actuate the butterfly valve 20 from its open to its closed position or-vice versa.

Near the lower end of the rod 35 a sector-shaped plate 42 is rigidly secured thereto and extends radially therefrom. A light coil tension spring 44 has its lower end connected to the plate 42 and its upper end connected to the lower portion of the armature 26 to urge the upper portion of the rod 35 into the bore 36 in the armature 26 in telescopic relation therewith.

A rectangular housing 45 is secured to the lower portion of. the cylindrical casing 23 at one side thereof, and a coiled thermostat 41 is mounted within the housing 45, one end of the thermostat being rigidly secured to a shaft 49 which projects through the side walls of the housing 45. An adjusting arm 50 is non-rotatably secured upon one of the projecting ends of the shaft 49 and the free end of this arm 50 is provided with securing means 52 by means of which the arm 56 may be held in the proper position to place an adjusting tension upon the thermostat 41.

The free end of the thermostat 41 projects into the lower portion of the cylindrical casing 23 and overlies the adjacent portion of the plate 42 as shown at 54.

The action of the thermostat 41 is such that when the thermostat is cold, the free end 54 will be in its lowest position relative to the casing 23 and as the temperature of the thermostat increases the free end 54 will rise in proportion to the increase in temperature. The bottom of. the casing 45 is left open and is positioned immediately above the exhaust manifold It) so that heat may readily be transferred from this manifold to the thermostat 41.

The operation of the device is as follows:

First, assuming that the motor is cold when started, the rod 35, the armature 26 and the free .end 54 of the thermostat 4! will all be in their lowest position and the butterfly valve 20 will be closed as illustrated in dotted lines. As soon as the engine starts, the vacuum created in the manifold l2 will exhaust the air from above the armature 26 causing the armature 26 to rise in the aperture in the solenoid 25. However, as the free end of the thermostat 41 is in its lowest position, it will bear upon the top of the plate 42 and maintain the rod 35 in its lowest position as illustrated in dotted lines. In this case, the rising of the armature 26 will stretch the spring 44 thereby imposing an upwardly directed force on the rod 35 to maintain the plate 42 against the lower surface of the free end 54 of the thermostat 41. As the temperature of the exhaust manifold l6 increases, heat will be transferred to the thermostat 41 and the free end 54 thereof will gradually rise permitting the spring 44 to raise 2138 rod 35 thereby gradually opening the valve If the effect of vacuum in the intake manifold l2 were alone depended upon to maintain the armature 26 in raised position when the engine is operating at normal temperature, a decrease in this vacuum effect caused by opening the throttle valve indicated by the letter T would permit the armature 26 to descend, thereby closing the valve 20 and cutting off the air supply to the carburetor. This would, of course, result in an immediate decrease in engine power and would probably have other very undesirable effects upon the engine. The solenoid 25 has been provided to obviate this difficulty, and as long as the engine is running and revolving the armature of the generator G, sufficient current will be produced by the generator to energize the solenoid 25 to maintain the armature 26 in raised position by the magnetic linkage between the armature and the solenoid. The connection to the solenoid has been made between the generator and the relay R. in order that the solenoid may be energized whenever the generator is operating and will be energized only when the generator is operating, manipulation of the ignition switch having no effect in energizing the solenoid and so that current will not leak back from the battery through the solenoid to the ground 28.

It is a further advantage of this construction that whenever the engine is stopped, the armature 26 and the rod 35 will immediately assume their lowest position, thereby closing the valve 20 to choke the carburetor [5. If the engine is started when hot, there will be an initial choking effect produced in order to give good starting performance to the engine. As soon, however, as the engine has started the armature 26 and the rod 35 will be immediately raised to their upper position, opening the valve 20, as the free end of the thermostat in that case is in its raised position and does not delay the upward movement of the rod 35 and plate 42.

In the form of the invention illustrated in Figure 2, the manifolds and the carburetor are the same as illustrated in Figure 1, except that in Figure 2 the carburetor is provided with two independently acting butterfiy valves 60 and 62 in the air intake thereof, and these valves 60 and 62 instead of having a spring tension valve such as the valve 2| illustrated in Figure 1, therein, are unbalanced. That is, they are eccentrically mounted on the shafts 63 and 64 so that suction induced in the carburetor will tend to open the valves sufliciently to allow a small amount of air to pass through the air intake into the carburetor, even when the valves 60 and 62 are in full choke position.

The choke control comprises, a coiled thermostat 65 mounted upon a shaft 66 which passes through and is rotatable in the side walls of a casing 61 which is secured by suitable bracket means immediately above the exhaust manifold I 0 and has an open bottom so that heat may readily be transferred from the exhaust manifold to the thermostat. One end of the thermostat is anchored to the casing at 68 and an arm 69 is non-rotatably mounted on one end of the shaft 66 outside of the casing 61. A bent rod or other suitable connecting means 10 is connected at its upper end to the free end of the lever 69 and at its lower end to the free end of an arm 12, the opposite end of which is non-rotatably mounted upon a projecting end of the shaft 64 of the valve 62.

From this description, it will be apparent that changes in the temperature of the exhaust manifold Ill causingthe thermostat to wind up and unwind will move the valve 62 towards its open or its closed position.

The control mechanism further comprises a cylindrical casing 76 mounted with its axis in of a bracket or suitable vertical position substantially in line with. the valve 6!] above the manifolds it and i2, and secured to a fixed part of the engine by means anchoring means. This casing 66 contains in the upper portion thereof, a solenoid 73 having an axial aperture it therethrough, one end of the solenoid being grounded at and the opposite end being connected to the lead from the generator G to the battery B between the generator and the relay or circuit breaker B. An armature it is mounted for vertical reciprocation in the aperture i and a rod 79 is rigidly secured in an axial bore in the armature and has its lower endprojecting below the lower surface of the armature. The lower end of the rod I9 is connected with the valve 60 by means of a bent rod 80 or other equivalent connecting means, the upper end of which is secured to the rod '69 and the lower end of which is secured to the free end of a lever 82 the opposite end of which isnon-rotatably secured to a projecting end of the shaft 63 upon which the valve 60 is mounted.

A vent 85 is provided in the top of the casing I6 and solenoid I3 to prevent air from becoming trapped above the armature I8 and causing a cushioning effect on the armature' It will be observed from this description that vertical movement of the armature 18 and the rod I9 will move the valve 60 towards its open or its closed position, and that the valve 60 moves independently of the thermostat 65 or the valve 62.

The operation of this form of the invention is as follows: If the engine is started when cold, the thermostat 65 will be wound up and the valve 62 will be closed as indicated in dotted lines in Figure 2. Also before the engine is started, the armature I8 and the rod I9 will be in their lowest position and the valve 60 will also be closed as indicated in dotted lines. As soon as {the engine has been started and the generator G starts to function, the solenoid 13 will be energized lifting the armature 18 and opening the valve 60'. The valve 62, however, will remain closed until sufficient heat has been transferred from the exhaust manifold to the thermostat 65 to cause the thermostat to unwind and raise the free end of the lever 69. This unwinding of the thermostat will occur gradually so that the valve @2 will be opened gradually as the temperature of the manifold it increases until, when the engine is operating at normal telnperature, the valve 62 will also be fully opened and the passage of air through the carburetor air intake will be unobstructed.

If the engine is now stopped, as soon as the generator ceases to function the armature 58 will drop closing the valve fit. The valve 62, however, will remain open and will gradually close as the thermostat 65 cools off. If the engine be restarted before the thermostat 65 has cooled off suiliciently to close the valve 62, a choking action on the carburetor will still be produced by the valve 68 which will be closed at the time of starting the engine. As soon as the engine starts however, and the generator begins to function, the armature 18 will be raised, thereby opening the valve 60 and as the valve 62 is already opened unobstructed passage of air through the air intake will be provided.

Having now described my invention and the principal objects and advantages thereof so that others skilled in the art may clearly understand the same, what I desire to secure by Letters Patent is as follows: In an automatic control for the choke valve of the carburetor of an internal combustion engine, a weighted armature tending to close said valve whenever the engine stops, a solenoid having one side thereof connected to the generator circuit between the generator and the generator relay for opening said valve whenever the engine starts and holding it open while the engine runs, a pneumatic connection from above said armature to the interior of the engine intake manifold whereby the vacuum produced in said intake manifold will assist said solenoid in opening said valve, a resilient connection between said armature and said valve, and thermostatic means acting upon the side of said resilient connection opposite said armature to delay the opening of said valve until a portion of the engine has reached a predetermined temperature.

EARL E. MOORE. 

